This invention relates to a process and composition for producing permanently water wettable, abrasion-resistant films on surfaces, and more particularly, to a process and carboxylic acid functional polymer composition for producing a permanently water wettable abrasion-resistant film on surfaces.
It is sometimes desirable that a surface of an article of manufacture exposed to water be water wettable. The term "water wettable" as used herein means the ability of the surface to retain a substantially unbroken film of water thereon. This property is desirable because a water wettable surface of an article of manufacture exposed to water condensation has a lesser tendency to drip droplets of water therefrom than a surface which is not water wettable. Instead of dripping in a random fashion from the surface, the water migrates downwardly along the surface in a predictable path, and if droplets form, they can be collected at a predetermined desired point.
Water wettable surfaces are utilized, for example, on refrigeration evaporators, various other evaporators, heat exchangers, surfaces which are maintained below ambient temperature in a humid atmosphere and which are susceptible to condensation and dripping, and the like. These surfaces are generally made from various metals, for example, aluminum, copper, iron and the like, and plastics, for example, polyethylene, polyvinylchloride and the like. Various examples of articles of manufacture in which water wettability is a desirable property, are disclosed in U.S. Pat. No. 4,163,702 and U.S. Pat. No. 4,181,773.
Various compositions and methods have been utilized to render metal surfaces temporarily water wettable, however, the deficiencies of such compositions and processes are pointed out in U.S. Pat. No. 4,163,702 and U.S. Pat. No. 4,181,773. It is always desirable to improve such surfaces and the coatings which are applied thereto.
As described above, it is generally desirable to produce water wettable surfaces where drainage of the moisture and water formed thereon is facilitated to prevent undesirable dripping conditions. In many instances, this is accomplished by providing the articles which have water-wettable coatings, with drainage slopes which are often aesthetically undesirable and/or have slopes which are too great to be utilized for their intended purpose. In certain areas and for certain purposes, odor problems appear to originate from surface conditions on many of the prior art surfaces, and it is desirable to provide surfaces where odor problems have been substantially reduced or eliminated but which maintain the characteristic of water wettability.
The processes and compositions of U.S. Pat. No. 4,163,702 and U.S. Pat. No. 4,181,773 overcome many of the foregoing disadvantages, however, it is desirable to improve coating techniques, such as, reducing the number of steps required to apply coatings to surfaces, reducing the cost of equipment and process parameters used in applying coatings to surfaces and providing compositions which can be applied as coatings to plastics as well as metals. In U.S. Pat. No. 2,467,341, there is disclosed a coating composition containing an acrylic resin as the primary binder together with up to about 80% to 90% silica to produce tough, continuous coatings. However, the compositions of U.S. Pat. No. 2,467,341 do not result in improvements in the process and compositions for producing permanently water wettable, abrasion-resistant films on surfaces because of the continuous nature of the coatings. In U.S. Pat. No. 2,467,342, vinyl resins in alcohol rather than water soluble carboxylic acid functional polymers are used for coating surfaces.